Amphibious vehicle

ABSTRACT

Amphibious vehicle comprises longitudinally mounted prime mover, transmission, and offset final drive; with drive outputs; and a power take off. Outputs drive front and rear differentials, via optional decouplers. Power take off powers drive tube, independently from co-axial rear propshaft. Tube powers sprockets via belt or chain; gears could be used here. Optional marine decoupler drives shaft, and thus water jet pump. A power train with front wheel drive only; a dead rear axle is provided. A power train with rear wheel drive only; a dead front axle is provided. Prime mover may be offset parallel to centre line; and may be an engine or an electric motor, possibly powered by a fuel cell. The power take off may be in the form of a drive spline.

[0001] The present invention relates to an amphibious vehicle capable oftravel on land and water, and more particularly to an amphibious vehiclein which a conventional automotive transaxle drive arrangement isadapted to drive at least one pair of road wheels and a marinepropulsion means.

[0002] In some known automotive power train arrangements the prime moverhas a power output shaft, typically an engine crankshaft, which isaligned substantially perpendicular to the longitudinal axis of thevehicle. This is known as a transverse engine layout. Normally, theengine will drive a transmission arranged in-line with the axis of thecrankshaft and which has all integral final drive and differentialoffset to the rear of the engine, the differential being connected bydrive shafts to the drive wheels of the vehicle. This arrangement iscommonly known as a transaxle drive and is usually employed with theengine located towards the front of the vehicle in order to drive thefront wheels of a vehicle. It is also known for such transverse powertrain arrangements to be adapted to provide four wheel drive by having apower take off from the transmission which drives the rear wheels of thevehicle through a rear differential.

[0003]FIG. 1 is a schematic plan view of a vehicle, indicated generallyat 10, having a such a known four wheel drive transverse engine andtransaxle arrangement. As can be seen, an engine 12 is mounted.transversely, that is with the crankshaft of the engine perpendicular tothe longitudinal axis of the vehicle, indicated at 15, forward of a pairof front wheels 14, 16 of the vehicle 10. A transmission 18 is mountedin-line with and is driven by the engine 12. Transmission 18 drives afinal drive, 20 which is offset to the rear of the vehicle. The finaldrive, 20 incorporates a differential and the front wheels 14, 16 aredriven from the differential by means of respective drive shafts 22, 24which may comprise CV joints (not shown) as is known in the art.

[0004] In order to provide for four wheel drive, the final drive has adrive spline 26 which drives a power take off unit 28. A propeller shaft30 is connected to the power take off unit 28 and transmits drive to arear differential 32, from which the rear wheels 34, 36 are driventhrough respective drive shafts 38, 40.

[0005] Four wheel drive, transverse engine, and transaxle drive units ofthe type shown in FIG. 1 are currently used by several large carmanufacturers in the production of private passenger vehicles and aretherefore produced in relatively high volumes, which makes thearrangement most procurable for use in an amphibious vehicle. Inchoosing a power train for a specialised low volume production vehicle,such as an amphibious vehicle, availability is an important factor.

SUMMARY OF THE INVENTION

[0006] It is an object of the present invention to provide an amphibiousvehicle in which a conventional four wheel drive transverse engine andtransaxle unit is adapted to drive at least one pair of road wheels anda marine drive means.

[0007] In accordance with the invention, there is provided an amphibiousvehicle having a power train comprising a prime mover, transmission,final drive, and a marine propulsion means, the final drive having apower take off, characterised in that: the prime, mover is positioned.with its output drive shaft arranged generally longitudinally of thevehicle and the final drive is arranged to drive at least one pair ofroad wheels of the vehicle through a differential, and in that the powertake off is adapted to drive the marine propulsion means via a drivetable.

[0008] Preferably, the power take off comprises a drive spline whichdrivingly engages one end of the drive tube.

[0009] Preferably, the final drive is arranged to drive a pair of frontwheels of the vehicle through a front differential. Alternatively, thefinal drive is arranged to drive a pair of rear wheels of the vehiclethrough a rear differential.

[0010] Conveniently, the final drive is arranged to drive two pairs ofroad wheels of the vehicle, each pair of road wheels being driventhrough a respective differential.

[0011] Advantageously, the drive tube is co-axial with a drive shaftwhich transmits drive from the final drive to a differential.

[0012] Preferably, one or more decoupler(s) is/are provided to allowdecoupling of drive to the road wheels, where said decoupler(s) is/arelocated downstream of the transmission.

[0013] Advantageously, the prime mover is positioned such that itsoutput drive shaft is generally in alignment with the longitudinal axisof the vehicle.

[0014] The prime mover may be an engine or an electric motor, the motormay be powered by a fuel cell.

[0015] Preferably, the final drive comprises at least one drive output,the axis of the at least one drive output being substantially parallelwith, but offset laterally from, the axis of the prime mover outputdrive shaft.

[0016] It is an advantage of the present invention that a conventionaltransverse engine and transaxle drive unit can be utilised and adapted.It is a further advantage that the conventional transverse engine andtransaxle drive unit can be positioned between the front and rear wheelsof the amphibious vehicle, and close to the rear of the vehicle, givinga rearward weight bias to the vehicle which is required for an optimummarine performance particularly when planing.

[0017] The invention will now be described, by way of example only, withreference to the Figures of the accompanying drawings in which:

[0018]FIG. 1 is a schematic view of a prior art vehicle;

[0019]FIG. 2 is a schematic plan view of an amphibious vehicle having apower train in accordance with a first embodiment of the invention;

[0020]FIG. 3 is a schematic plan view of an, amphibious vehicle having apower train in accordance with a second embodiment of the invention; and

[0021]FIG. 4 is a schematic plan view of an amphibious vehicle having apower train in accordance with a third embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0022] FIGS. 2 to 4 show various embodiments of an amphibious vehicle inaccordance with the invention, in which the conventional engine 12,transmission 18 and final drive 20 arrangement as described in relationto FIG. 1 has been utilised and adapted. Common reference numerals havebeen used throughout to designate parts in common with parts shown inFIG. 1.

[0023] Referring firstly to FIG. 2, there is shown an amphibious vehicle41 having a power train 42 in which an engine 12, with an in-linetransmission 18 and offset final drive 20 are positioned with thecrankshaft of the engine in alignment with the longitudinal axis 44 ofthe vehicle. The final drive 20 incorporates a differential having driveoutputs 21, 23. A rear differential 48 is connected to one of the driveoutputs 21 by means of a propeller shaft 52 and drives a pair of rearwheels 34, 36 of vehicle through drive shafts 3 8, 40 and relay shaft39. A forward differential 46 is connected to the other of the driveoutputs 23 by a further propeller shaft 50 and drives front wheelpropeller shaft 50 and drives front wheels 14, 16, by means of driveshafts 22, 24 and a relay 25. The road wheel drive shafts may compriseCV joints (not shown) as required.

[0024] In order to enable selective engagement of drive to the front andrear wheels independently, a front decoupler 54 is positioned in thedrive line between the propeller shaft 50 and the front differential 46,and a rear decoupler 56 is positioned. in the drive line between thepropeller shaft 52 and the rear differential 48. The front and reardifferentials 46,48 can therefore, be selectively coupled and decoupledfrom the final drive differential 20.

[0025] Although not shown, an alternative arrangement for selectivelycoupling drive to the front and rear wheels independently comprisesproviding a decoupler in the drive line between each of the front andrear differential 46, 48 and at least one of the road wheels driven bythe respective differential. In this alternative arrangement, thedecouplers 54, 56 as shown in FIG. 2 are not required, and the front andrear differentials 46, 48 are driven directly from the final drive 20 bytheir respective propeller shafts 50, 52. Where a decoupler isincorporated into a drive line between a differential and a road wheel,the decoupler may be fitted in series or in combination with a CV jointused in the drive line. For example a combined CV joint and decouplerarrangement such as that disclosed in the applicant's co-pendingInternational patent application PCT/GB01/03493 could be used.

[0026] Drive for a marine propulsion means, which in this case is awater jet 70, is also taken from the final drive 20 by means of a drivetube 58 positioned around, and co-axial with the propeller shaft 52,which runs at the side of and parallel with the engine 12. One end ofthe drive tube 58 is splined, and mates with a drive spline 26 providedon a spline carrier. The spline carrier is arranged concentrically aboutthe drive output 21 of the final drive 20 and the arrangement is suchthat the drive tube 58 is driven by the drive spline 26 independently ofthe propeller shaft 52. The other end of the drive tube 58 drives adriving sprocket 60. A sprocket 62 is driven by a belt or chain 64 fromthe driving sprocket 60, and is connected by a decoupler 66 to a driveshaft 68 of a water jet unit 70. The decoupler 66 enables the drivensprocket to be selectively coupled and decoupled to or from the driveshaft 68, in order to allow drive to the water jet to be disconnectedwhen the vehicle is being operated on land and marine drive is notrequired.

[0027] A bearing (not shown) may be required to locate the rear end oftube 58, and sprocket 60. As an alternative to the sprockets and belt orchain shown, a series of typically three gears could be used to transferdrive from tube 58 to shaft 68. Whilst a water jet is the preferred formof marine propulsion means, this is not essential and the water jet maybe replaced with any suitable marine propulsion means, for example a inmarine screw propeller.

[0028] In this and the other embodiments described below, the finaldrive has a power takeoff in the form of a drive spline formed on aspline carrier and the drive tube is provided at one end with acorresponding, spline for engagement with the drive spline. However,those skilled in the art will understand that means other than a drivespline can be used to transfer drive from the power take off carrier tothe drive tube. For example the carrier and the drive tube could beprovided with inter-engagning lugs or gear teeth. Alternatively, thedrive tube could be welded, bolted or otherwise secured to the carrier.

[0029] Referring now to FIG. 3, a second embodiment of an amphibiousvehicle 141 in accordance with the invention comprises a power train142. The power train arrangement 142 shown in FIG. 3 is generallysimilar to the power train 42 as described above with reference to FIG.2, the main difference being that only the front wheels 14, 16 of thevehicle are driven from the final drive 20. Thus, propeller shaft 52,decoupler 56 and rear differential 48 of the FIG. 2 arrangement areomitted, as they are not required in this embodiment. In place of thelive, or driven axle shown in FIG. 2, a dead, or non-driven axle 72 isfitted to the rear of the vehicle. Alternatively, the rear wheels can beindependently mounted to the vehicle body or chassis.

[0030] CV joints 74, 76 are incorporated in the drive line between thefront differential 46 and each of the front wheels. Decouplers may befitted in series or in combination with these CV joints, in order todecouple the front wheels from the transmission during marine use.

[0031] Referring now to FIG. 4, a third embodiment of an amphibiousvehicle′241 in accordance with the invention comprises a power train242. The power train arrangement 242 shown in FIG. 4 is generallysimilar to the power train 42 described above in relation to FIG. 2, themain difference being that only the rear wheels are driven from thefinal drive 20. Thus, in the power train 242, propeller shaft 50,decoupler 54 and front differential 46 are omitted, as they are notrequired. In place of the live, or driven axle shown in FIG. 2, a dead,or nondriven axle 82 is fitted to the front of the vehicle.Alternatively, the front wheels can be independently mounted to thevehicle body or chassis,

[0032] CV Joints 84, 86 are located in the drive line between the reardifferential and each of the rear wheels. Decouplers may be fitted inseries or in combination with these CV joints, in order to decouple therear wheels from the transmission during marine use.

[0033] In the second and third embodiments described above with respectto FIGS. 3 and 4, if the final drive 20 incorporates a differential,then the differential is locked up so that only the fitted propellershaft 50 or 52 is driven. It should be noted that either of thesearrangements could be suited to a three-wheeled vehicle. Equally, thefirst embodiment could be adapted to use in a six-wheeled vehicle by useof a tandem rear axle.

[0034] In all the embodiments of the invention described above, theprime mover is provided the form of an engine. The engine can be of anysuitable type and may comprise a piston engine, a rotary engine orturbine and can be adapted to run on any suitable fuel such as petrol,diesel, gas, or liquid petroleum gas (LPG). However, it should beunderstood that the invention is not limited to power trains in whichthe prime mover is an engine but is intended to cover power trainshaving a prime mover of any suitable type. For example the prime movercould be an electric motor or it could be in the form of a hybridcombination of an engine with an electric motor. Where the prime movercomprises an electric motor, the electric motor could, for example, bepowered by a fuel cell.

[0035] Whereas the invention has been described in relation to what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not limited to thedisclosed arrangements but rather is intended to cover variousmodifications and equivalent constructions included within the spiritand scope of the invention as defined in the claims. For example, itwill be appreciated that further combinations of driven axles anddecoupler locations may be selected from the options disclosed above.Also, whilst it is preferred that decouplers are provided in the driveline between the transmission and the driven road wheels, this is notessential and the decouplers, can be omitted. Similarly, whilst it ispreferred that a decoupler be provided to enable drive the marinepropulsion means to be disconnected when the vehicle is being used in aland mode, this is not essential and the marine propulsion meansdecoupler can be omitted if desired. Furthermore, whilst in theembodiments described the output shaft of the prime mover is shown inalignment with the longitudinal axis of the vehicle, this need not bethe case and the output shaft could be arranged so as to lie generallyparallel to, but offset from, the longitudinal axis of the vehicle ifrequired.

1. An amphibious vehicle having a power train comprising a prime mover,transmission, final drive, and a marine propulsion means, the finaldrive having a power take off, characterised in that: the prime mover ispositioned with its output drive shaft arranged generally longitudinallyof the vehicle and the final drive is arranged to drive at least onepair of road wheels of the vehicle through a differential, and in thatthe power take off is adapted to drive the marine propulsion means via adrive tube that extends alongside the prime mover.
 2. An amphibiousvehicle as claimed in claim 1, in which the power take off comprises adrive spline which drivingly engages one end of the drive tube.
 3. Apower train as claimed in claim 1, in which the final drive is arrangedto drive a pair of front wheels of the vehicle through a frontdifferential.
 4. A power train as claimed in claim 1, in which the finaldrive is arranged to drive a pair of rear wheels of the vehicle througha rear differential.
 5. An amphibious vehicle as claimed in claim 1, inwhich the final drive is arranged to drive two pairs wheels of thevehicle, each pair of road wheels being driven through a respectivedifferential.
 6. An amphibious vehicle as claimed in claim 1, in whichthe drive tube (58) is co-axial with a drive shaft which transmits drivefrom the final drive to a differential.
 7. An amphibious vehicle asclaimed claim 1, in which one or more decoupler(s) is/are provided toallow decoupling of drive to the road wheels, where said decoupler(s)is/are located downstream of the transmission.
 8. An amphibious vehicleas claimed in claim 1, in which the prime mover is positioned such thatits output drive shaft is generally in alignment with the longitudinalaxis 4 of the vehicle.
 9. An amphibious vehicle as claimed in claim 1,in which the prime mover is an engine.
 10. An amphibious vehicle asclaimed in claim 1, in which the prime mover is an electric motor. 11.An amphibious vehicle as claimed in claim 10, in which the electricmotor is at least partially powered by a fuel cell.
 12. An amphibiousvehicle as claimed in claim 1, in which the final drive comprises atleast one drive output, the axis of the at least one drive output beingsubstantially parallel with, but offset laterally from, the axis of theprime mover output drive shaft.